Method of forming printing surfaces on cylinders



Nov. 17, 1936. R SCHULTZ 2,060,828

METHOD OF FORMING PRINTING SURFACES ON CYLINDERS Filed Oct. 5, 1932INVENTOR ATTORNEY Patented Nov. 17, 1936 UNITED STATES PATENT OFFICEMETHOD OF FORMING PRINTING SURFACES ON CYLINDERS Application October 5,1932, Serial No. 636,261

Claims.

This invention relates to an improved method of forming printingsurfaces on cylinders.

Printing cylinders having intaglio or half tone printing impressions inthe surface thereof produced by etching, invariably differ in tonalqualities due to the operators inability to control the etch. This lackof uniformity is highly objectionable where exact duplicatereproductions are desired, which must be produced from two or printingand tonal values.

An object of this invention is to provide a method of forming printingsurfaces on cylinders in which the depth of the tonal values isdefinitely controlled.

Still another object of my invention is to provide a method for making aprinting cylinder having a continuous and jointless printing surfacethereon.

Another object of my invention is to provide a method of forming aphotographically toned printing surface on a cylinder by which the depthand printing characteristics of the tonal recesses may be definitely anduniformly controlled in a simple, practical and economical manner toprovide a printing surface from which a very high quality of printingmay be produced.

Other objects of this invention will become apparent as the disclosureproceeds.

Although the novel features which are believed to be characteristic ofthis invention will be particularly pointed out in the claims appendedhereto, the invention itself, as to its objects and advantages, and themanner in which it may be carried out, may be better understood byreferring to the following description taken in connection with theaccompanying drawing forming a part thereof, in which Fig. 1 is aperspective view of a printing cylinder as it appears prior to theapplication of the printing surface thereon; 1

Fig. 2 shows the printing cylinder mounted on a frame and illustratesone step in the process of forming the printing surface on the cylinder;

Fig. 3 is an enlarged cross sectional view of a fragmentary portion ofthe printing cylinder, this view illustrating another step in theprocess of casting the printing surface thereon;

Fig. 4 is a view similar to Fig. 3 and illustrates 5 a further step inthe process of casting or moulding the printing surface on to thecylinder;

Fig. 5 is an enlarged cross sectional view of a fragmentary portion ofthe printing cylinder with the printing surface moulded thereon, certain10 irregularities being shown greatly distorted and enlarged forpurposes of illustration; and

Fig. 6 is an enlarged cross-sectional view of a portion of the cylindershowing the integral continuous character of the molded printingsurface. 15

Similar reference characters refer tosimilar parts throughout theseveral views of the drawing.

I have shown in Figure 1 a cylinder having a core or body portion l0which may be formed of metal or any other suitable rigid material. Shaft20 portions II project from each end thereof and are suitably shaped tofit the journals provided therefor in the printing press. A backinglayer l2 of suitable material, such as a nitro-cellulose or celluloseacetate composition, covers the core portion ill of the cylinder. Thebacking layer may be moulded on to the cylinder in a number of ways. Byway of example, the layer l2 may be applied by spraying or painting thebacking material on to the core while in a plastic or 30 fiowablecondition. The cylinder may then be placed in a lathe and cut or groundand polished so as to present a. surface perfectly round, continuous andsmooth. As a more practical and effective method of coating thecylindrical core 35 NJ, the core may be passed through a suitableaperture provided in a vat containing the backing material insemi-liquid condition. Means are provided around the aperture and withinthe vat for distributing the cellulose material smoothly 40 and evenlyaround the core. One or more applications may be necessary to obtain theproper thickness. A backing layer of approximately eight one-thousandthsof an inch has been found sufficient for. effective: rotogravureprinting al- 45 though the thickness of the layer may be varied withinwide limits.

In applying the printing surface to the coated cylinder shown in Figure1, the cylinder is rotatably mounted in a suitable frame having trun- 50nions l3 in which the shafts I l rotate. The trunnions l3 are supportedon legs or standards M. A crank l5 may be secured to one end of theshaft H for rotating the roll In in the trunnions l3, although it willbe appreciated that any suitable driving apparatus, including necessarygearing, may be made use of.

A copy relief or matrix having a moulding surface I! is clamped orsecured at one end thereof against the backing layer l2 of the printingcylinder II). For this purpose one or more adjustable clamping membersl8 are provided which grip the end of the copy relief and press it downagainst the cylinder. Other well known means for positioning the end ofthe copy relief in fixed relationship to the cylinder may be used,clamping members 18 being shown for illustrative purposes only.

The matrix may comprise a backing sheet it of celluloid or otherflexible material, and the molding surface l'I may comprise waterswollen gelatine which has previously been sensitized, exposed and waterswollen to form the molding surface I! in relief thereon. Reference ishere made to my co-pending application, Ser. No. 518,649, filed February27, 1931. In general such a relief surface is produced by photographingthe object to be produced and exposing the sensitized gelatine surfacethrough the photographic plate carrying the object image. The objectimage may be screened with a half tone or intaglio screen either byexposing the photographic plate through the screen in the camera, or byexposing the sensitized gelatine to light passing through the screen inthe printing frame. After exposure, the screened photographically tonedsensitized gelatine is then immersed in a tank of water,

, causing the unexposed portions of the gelatine to swell and form arelief surface carrying the screened image in reverse thereon. A waterswollen gelatine copy relief is thus produced which carries thephotographically toned image in minute detail. The half tone or intaglioscreen need not be used if unscreened images are desired. It is alsounderstood that, if desired, a portion only of the subject to be printedmay be screened by subjecting corresponding selected portions of thesensitized gelatine to the action of the half tone screen, leaving otherportions of the gelatine unscreened. While the water swollen gelatinecopy relief above described provides an excellent matrix carrying thefinest image details which can be made quickly and economically, it isunderstood that other relief matrices can be used in the casting processherein described. The printing circumference of the cylinder issufficient in size to receive the full printing impression to bereproduced. The ends of the copy relief matrix may be provided with amargin, border or trim l'la to provide a smoothnon-printing marginalsection I90 extending longitudinally across the cylinder adjacent themeeting ends of the matrix.

Compositions which have given eminently satisfactory results in actualservice have been formed from a cellulose base reduced to a viscous,plastic state by a suitable solvent or solvents. More particularly, sucha composition may be made by dissolving nitro-cellulose or celluloseacetate in a suitable solvent, such as acetone, ethyl acetate, butylacetate, amyl acetate, butyl alcohol and similar Well known solvents incommercial use. In order to get a plastic which will flow at the desiredrate for molding purposes when a particular solvent is used and toobtain a liquid composition containing total solids of 20% to 50% ormore, it is preferable to use a mixture of cellulosic bases. Aplasticizer may be added but a plasticizer should be selected which willnot materially decrease the hardness of the finished product. Preferredplasticizers for cellulose nitrate are tricresyl phosphate, triphenylphosphate, or ditbutyl phthalate, and for the cellulose acetate I findthat triacetin is a satisfactory plasticizer. These plasticizers, whenused in the small amounts needed, appear to have very little effect onthe hardness of the finished material, and yet give the material thedesired plasticity and toughness. These improved cellulosic compositionsare peculiarly adapted for the purposes of the present invention in thatthe compositions give a hard, resilient and tough product which wearswell and which will receive and retain the finest impressions underconditions of use. Various resins rendered plastic by suitable solventsso that they can be molded in a relatively cold condition may also beused. It is understood that various materials initially moldable andadapted to take the impressions from the copy relief and maintain thesame upon solidification are encompassed within the term plasticizedmaterial or moldable composition.

The backing layer I2 should be formed of a composition which willreadily adhere to the cylinder and also form a strong bond to immutablysecure the printing surface l9 to the cy nder.

When a cellulose printing surface i9 is used the backing layer l2 mayalso be formed of cellulosic material, and where a moldable resin isused as the printing surface, the backing layer l2 may likewise beformed. from material having a resinous base. In moulding thecomposition l9 which is to form the printing surface on to the cylinder,the composition, in a plastic, semi-fluid viscous state, is poured onthe cylinder in the position shown in Figure 2, and is squeegeed forwardas the cylinder is rotated. A pressure roller 20 is mounted to rotate ina journal 2| provided at the upper end of an arm 22 of a pair of bellcrank levers fulcrumed at 23 to the standard H.

To regulate the pressure exerted by the roller 20 against the copyrelief, a weight arm 24, ex tending from each of the arms 22, isprovided. A weight 25 rides on each of the arms 24 and the pressureexerted by the roller 20 can be regulated by adjusting the position ofthe weight.

A quantity of the moldable mass [9 is placed in position on the cylinderand immediately in advance of the molding face of the copy relief ormatrix. Thereafter, the weight 25 is so adjusted on the arm 24 as tocause the roll 20 to bear against the matrix with desired pressure,forcing the relief surface I! of the copy relief into the moldable mass.Upon rotation of the cylinder, the mass is spread over the backing layerl2 of the cylinder and a moulding of the mass to conform to the reliefis effected.

The roll 20 is preferably laterally offset with respect to the verticalso that the moldable material I9 will remain in position on top of thecylinder. The printing surface l9a is thus moulded under uniformconditions of pressure, the material l9 being squeegeed into positionunder the copy relief in a manner such as to drive out any air bubblescontained therein, and which will give a uniform printing surface "la.The printing surface la is made suflicient in thickness to carry thefull depth of the molding impressions in the matrix.

A gelatine or paper strip or other material 30, to which the materialI!) will not adhere, is placed over the starting end of the matrix, asshown in Figures 3 and 4. When the roll 40 has completed its revolution,and the pressure roll 20 reaches the starting end of the matrix, the

cation of heat.

plasticized mass I9 is squeegeed or forced by the pressure roller 20 uponto the non-sticking gelatine strip 30, if any excess be present. Thematerial I9 is forced up against the end edge of the matrix comprisingthe backing l6 and the relief surface ll, and in so doing a little spinel9b, substantially of knife-like fineness, may be formed which extendslongitudinally across the roll.

When the printingsu'rface l9a has been completely formed, the surface ispermitted to harden and set, which requ'ires'approximately. 10 to 30minutes when a moldable cellulosic mass is used. The time element will,ofcourse, vary with the moldable material used. When the printingsurface l9a has set to a sufficient degree, the pressure roll 20 islifted off from the matrix by means of a handle '26. The matrix i6 isthen stripped from the roll. The fin W1) is then removed and the surfacemade smooth and concentric. The fin I9!) is preferably removed byscraping with a sharp knife or blade, which is suitably supported in aholder to permit the fin to be planed off to the proper surface level,after which the surface covered thereby is polished so as to present anonprinting surface l 90 which extends in a relatively narrow stripacross the surface of the printing cylinder. The fin lab, formed by theabove method, is so small and fine that no dimculties are encounteredwith respect to its removal.

The printing surface iBa, as illustrated in the drawing, may beconsidered an intaglio printing surface, but it is readily understoodthat a half tone or relief printing surface screened, unscreened, oronly partly screened, may be molded from a matrix which has beencorrespondingly prepared. When completed the printing surface la and thenon-printing surface We is continuous and unbroken, since the meetingends of the moldable mass it become merged and flow together while themass is still plastic, resulting in a molded layer free from any seam orjoint.

The cylindrical printing surface is thus formed in situ, in oneoperation and without the appli- The resulting composite printingcylinder comprises a metallic body, a backing layer formed thereto, anda superimposed initially cold plastic composition which during theconforming process has also had imparted thereto a desired printingsurface. The particular method and apparatus herein disclosed has beenfound to give excellent results in service. The printing cylinder may bereused by regrinding the cylinder to smoothness or removing thecomposition with a suitable solvent. When the printing surface iscomposed of cellulose material, amyl acetate solvent may be used toremove the same. A new printing surface may then be applied by themethod described, or the new printing surface may be superposed on theoriginal printing surface, depending on the thickness of the rolldesired.

While certain novel features of the invention have been disclosed andare pointed out in the annexed claims, it will be understood thatvarious omissions, substitutions and changes may be made by thoseskilled in the art without departing from the spirit of the invention.

What is claimed is:

1. The improved process of forming printing surfaces on cylindersincluding attaching one end of a copy relief to the surface of acylinder, placing a plastic composition on said cylinder in advance ofsaid copy relief, and thereafter rolling said copy relief over and uponsaid cylinder so as to force out the excess plastic and mold theprinting impressions carried by said copy relief in the plasticcomposition retained upon the cylinder.

2. The improved process of forming printing surfaces from cellulosicplastics, including attaching one end of a copy relief to a backing,placing a cold-plasticized cellu1os1c composition on said backing and inadvance of said copy relief, and thereafter rolling said copy reliefover and upon said backing, whereby to force out excess plastic andimpart the desired printing surface to the material retained upon thebacking, and thereing and the copy relief so as to mold the printingimpressions carried by said copy relief in the plasticized compositionretained upon the cylinder, stripping off the said copy relief from thefinished surface, and removing the fin formed at the meeting ends of thecopy relief.

4. An improved method of forming printing surfaces on cylindersincluding, securing one end of a copy relief strip to said cylinder withthe impression side of said strip adjacent the cylinder, placing a massof plasticized cellulosic material on said cylinder and in advance ofsaid copy relief on said cylinder whereby said plasticizing material issqueegeed between the cylinder and the copy relief, forced into intimateadhering contact with the cylinder, and molded by the copy relief,stripping off the said copy relief from the finished surface, andremoving the fin formed at the meeting ends of the copy relief.

5. The improved-process of forming printing surfaces oncylindersincluding, providing a copy relief having printing impressionsin reverse in the surface thereof, placing plasticized material betweenthe impression sideof said copy relief and the cylinder to be treated,rolling said cylinder and copy relief together so as to force out theexcess plasticized material therebetween and mold the desired printingimpressions in the plasticized material retained upon' the cylinder.

6. The improved process'of forming printing surfaces on. cylindersincluding, providing a copy relief having printing impressions inreverse in the surface thereof, placing a plasticized composition onsaid cylinderiinadvance of said copy relief, and thereafterrolling saidcopy relief over and upon said cylinder so as to force out the excessplasticized material and impart the desired printing surface to thematerial retainedv upon the cylinder and removing the fin formed in thematerial at the meeting ends of the copy relief.

7. An improved method of forming cylindrical printing surfacesincluding, providing a copy relief having printing impressions inreverse in the surface thereof, imposing a predetermined mass ofplasticized cellulosic material upon said cylinder and in advance ofsaid copy relief, and thereafter pressure rolling said copy relief onsaid cylinder and said plastic material, whereby said material issqueegeed between the backing surface and the copy relief surface andforced into intimate contact with the backing surface and molded withthe impressions carried by said copy relief.

8. An improved method of forming a cylindrical printing surfaceincluding, providing a copy relief having embossed impressions therein,placing a plasticized cellulosic material between the embossed side ofsaid copy relief and the cylinder to be treated, rolling said cylinderand copy relief together whereby the plasticized material is squeegeedbetween the cylinder and the copy relief surface, forced into intimateadhering contact with the cylinder and embossed by the copy relief,stripping off the said copy relief from the finished surface, andremoving the fin formed at the meeting ends of the copy relief.

9. An improved method of forming cylindrical printing surfacesincluding, forming a backing layer upon the surface of a cylinder,fixing an end of a copy relief strip to the cylinder surface,

cylinder and said plastic material so as to mold the printingimpressions carried by said copy relief in the plastic material retainedupon the cylinder.

10. The improved process of molding a printing surface on a cylinderincluding, providing a water swollen gelatin copy relief havingphotographically toned printing impressions in reverse in the surfacethereof, placing a moldable material on said cylinder in advance of saidcopy relief, and thereafter rolling said cylinder and copy relieftogether so as to mold the printing impressions carried by said copyrelief in the moldable material retained upon the cylinder.

OSWALD R. SCHULTZ.

